The present invention relates to container end panels, particularly of the type that are used for the packaging of products under high pressure, such as beer and/or carbonated beverages. In recent years, many foods and beverages, particularly carbonated beverages and beer, have commonly been packaged in metal containers formed of either aluminum or steel.
In the manufacture of such containers for packaging foods and beverages, it is essential that the containers be formed of a minimum thickness of metal so that the container can be marketed at a competitive price. The cost of the container is extremely important since, for many products, the cost of the container approaches or exceeds the cost of the product being packaged therein. As such, any reduction in cost of manufacturing containers is extremely desirable.
Furthermore, because of the large market for metal containers, particularly those formed of aluminum, a very small savings in the amount of material for a single can will produce a substantial difference in price in considering a normal order from a packager, which may include hundreds of thousands of containers. Thus, if the container manufacturer can reduce the thickness of the metal utilized in forming the container by even one-thousandths of an inch, the cost savings can be substantial.
In more recent years, many beverages have been packaged in what is commonly referred to as a two-piece container. In this container, the bottom wall and side wall of the container are formed as an integral unit by drawing and ironing or extruding a flat blank to produce a container open at one end. The open end of the container then has an end panel secured thereto by a conventional seaming process.
These types of containers must be capable of withstanding pressures on the order of 90 p.s.i. minimum without having any portion of the container buckle.
Various proposals have been made for increasing the resistance to buckling of an end panel by particular configurations of the end panel. One example of such configuration is disclosed in U.S. Pat. No. 3,417,898, issued Dec. 24, 1968.
Since even a small reduction in metal thickness for either the container end panel or the container body can result in significant savings, container manufacturers are constantly striving for reducing the amount of metal required for producing the container, without sacrificing any of the characteristics, such as reduced buckling pressure.